


It's Not You

by Filmsterr



Category: Supernatural
Genre: Alpha Dean, Alpha/Beta/Omega Dynamics, Alternate Universe - Soulmates, Angst, Beta Lisa Braeden, Castiel in Heat, First Meetings, Happy Ending (kind of), Infidelity, M/M, Married Dean, Omega Castiel, Shower Sex, True Mates
Language: English
Status: Completed
Published: 2017-09-26
Updated: 2017-09-26
Packaged: 2019-01-05 21:10:48
Rating: Mature
Warnings: No Archive Warnings Apply
Chapters: 1
Words: 5,147
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/12197496
Author URL: https://archiveofourown.org/users/Filmsterr/pseuds/Filmsterr
Summary: Dean had done everything right. He’d waited.He’d given up hope on the whole true mates thing when he was about twelve, becausecome onshit like that didn’t happen outside the movies. So he'd gone off and done the right thing. He married a pretty girl, bought a house, had a pup.And then he caught the scent.





	It's Not You

**Author's Note:**

> Disclaimer: This is the first time I've ever written anything with A/B/O dynamics (technically- I've been told some other my other works resemble the concept) and it's not my area of expertise. Maybe something things don't line up, sorry about that. I've just been reading a few fics lately, and when inspiration strikes, you go with it. I'd love to hear what you think about my voyage into (personally) unchartered territory. Let me know with the comments and kudos button below. xoxo

It wasn’t supposed to be like this. 

Dean had done everything right. He’d waited.

He’d given up hope on the whole true mates thing when he was about twelve, because _come on_ shit like that didn’t happen outside the movies. But even still, he left room for the unlikely event that maybe he would chance upon some guy or girl who made his biology light up like a pinball machine.

He’d dated, pretty much consistently from the time he was fourteen, and he’d even had some serious relationships-- but it had never lined up exactly right. Each time there was always something missing, some final thing that when he got down to it made a reasonable excuse to cut and run. 

He’d waited until he was almost thirty to get married, and even then it was because Lisa had gotten pregnant. Not that he wasn’t happy. He often felt like he’d stumbled into this perfect, ready-made kind of life; like he was just some lucky bastard of a schlub, and that this gorgeous woman he’d ended up married to had no idea how much better than him she could do. 

Life was good. Dean now felt that he could say for certain that there was no more perfect match for him out there in the world. They got along so easy, never fought about anything. And together with Ben, they had a real good thing going here. This was it, this was his life-- and it was a damn good one. 

And then one day he was at the gym, sweat pouring of him as he jogged a steady rate on the treadmill, when he caught this scent. It made him whip his head up so fast so that he lost all track of where he was and he almost fell flat on his face because of the belt moving underneath him. He darted his eyes all over the room to find it, seek it out, and there were suddenly all these thoughts at the front of his mind telling him things like _mate fuck claim mine_. 

The next thing he knew he was locked in a shower stall with his hands down some omega’s shorts, got him pinned against the wall and panting raggedly in his ear. His teeth were marking up the pure, smooth white skin of his neck and the guy was whining for him, begging like Dean was the only thing holding him onto this earth. 

Guilt washed over Dean like a giant, crippling wave, and without even thinking the words he heard himself saying, “Wait, wait…”

The guy-- his _mate_ , his true mate-- looked up at up with eyes that were so big and wide, and he thought they’d probably be beautiful and captivating if his pupils weren’t blown out with arousal right then. And his mouth, his lips were so full and dark pink, and his teeth kept biting down on them in the sexiest way Dean could ever imagine. 

“What, what is it?”  

A picture of Lisa, waiting for him at home, sprung to his mind. It was gone more quickly than he would like to admit to himself. 

“Fuck it,” Dean cursed, and tugged down the guy’s shorts to get back to what his body was shouting at him to do. 

When it was over, and they were finished and stained with come and sweat, leaning on each other for support and heaving loud breaths of air, the guy took Dean’s face into his hands and started to line kisses up and down his jaw. 

“I can’t believe it,” he said, and it was hard for Dean to comprehend how a voice so deep could be soft, reverent like that. “I can’t believe you’re here. I waited so long, and I… I didn’t think you existed.”

Dean huffed out a laugh. He felt vaguely like he was having an out of body experience, like he was watching all this happen to someone who wasn't him. He didn’t hear the words leaving his own mouth. “I know. Me either.”

It was more true than this guy could possibly know. 

For six years, Dean had been the most faithful of husbands to Lisa-- he’d never even thought about cheating. Sure, he’d occasionally walk by some hot young thing in the grocery store and take a minute to appreciate their ass. But he’d never acted on it, never wanted to. 

And now here he was, buried balls deep in some man who he’d never seen before in his life. 

He reached into Dean’s pocket and pulled out his cellphone. If he saw anything that upset him, he didn’t indicate it, though Dean doubted that he would. Dean wasn’t the type to have a picture of his wife as the background on his phone-- though, something in him told him that he wouldn’t mind having several hundred photos of the man still in his arms on him at any given moment. 

His cock pulsed inside the man, and the omega’s face lit up in delight as he handed the phone back to Dean. “Here’s my number,” he smiled, “I already sent myself a text. So you just let me know when we can see each other again.”

He leaned in for another kiss that Dean allowed himself to be given. He liked the way this guy felt in his arms, against his lips. On his cock. God, it had been the best sex he’d ever in his goddamn life, and it had only just been a quickie. He wondered what it would feel like to have this guy around during one of his ruts. He stopped himself before his dick could spring back into action at the idea of it. 

Dean’s eyes fell to the phone in his hands and surveyed his new contact info. “Castiel,” he read aloud.

“Yeah,” his mate blushed, and Dean wanted to nuzzle into his neck and scent that sweet spot, “It’s a bit of a weird name, I know. You can call me Cas if you like.”

(----)

He wished his resolve was stronger. He wished that he’d stared at the phone for days, wrestled with himself, until he finally broke down. But that wasn’t the case. Instead, he’d texted Cas the next morning, after Lisa had kissed him goodbye and told him to have a good day at work. He couldn’t wait to see him, scent him, touch him. 

He hadn’t even had a god damn conversation with the guy yet. He was afraid to. Afraid that they would get to know each other, and he’d be even more perfect than Dean was imagining, and then he’d be shit out of options, wouldn’t he? 

But he did have to be honest. He couldn’t… he just couldn’t go on keeping all of that inside him.

(Part of him knew that he couldn’t lie to Castiel. He didn’t seem to have the same overwhelming need to confess to Lisa. He pushed that thought deep, deep down into the trenches of his mind. He's think about that later. He couldn’t afford to be honest with _himself_ right now, after all.)

Dean told him everything as soon as he got over to Cas’ cozy, well-decorated apartment. He’d ditched work to stop by in the afternoon. He was becoming so reckless these last two days, he didn’t even recognize himself. 

He burst through the door and laid it all out on the table, and he could honestly say that it made no fucking difference at all in the amount of guilt that was weighing on him constantly since the shower scene yesterday. 

He was surprised by how quickly Cas dissolved into a crying mess on the sofa. He was also surprised by the effect that set off in himself, an incredible, all-encompassing need to make up for that fact. His alpha urges shouted at him to comfort his omega, build a nest of pillows and make him a tea and hold him tight and kiss him until the tears stopped and it would all be okay again. 

He clenched his hands into fists and tried to withhold that urge. 

But he did try to take Castiel by the shoulders, lead him gently to the couch. 

“I knew it,” the omega sniffled through his tears, “I knew this was all too good to be true. It couldn’t all be this easy, like some… some fairy tale or something.”

Dean wished that it could be. He wished that Cas’ true mate had been someone other than him, someone who could swoop in and claim him right away, and he wouldn’t have to waste a seconds’ tears on a piece of shit like Dean. 

Of course, the idea of Cas being with anyone else also set off his alpha territorial instincts and he started to emit a deep, rumbling growl. Castiel looked up and him and shivered, which made Dean realize what he was doing and stop immediately.

“I’m so sorry, Cas. I… I didn’t know. I’d given up…” he scratched at the hairs on the back of his neck, “I thought it was stupid to keep hoping.”

Castiel looked up at him, his eyes transformed by the sadness. They were so beautiful that Dean had to choke back a gasp. 

“I can’t blame you,” he muttered, curling up into himself. “I felt the same. It’s… it’s not your fault.” 

But it was. Dean was failing to take care of Cas, to ensure his absolute security and happiness. He was a shit alpha, a fucking terrible awful no good fucking one. 

And let’s not even begin to talk about what kind of husband he was.

Castiel swallowed loudly a big bubble of tears that had been sitting in his throat. He stared at the coffee table and a weak smile formed on his lips. Dean’s instinct told him to run a hand through Cas' soft, black locks. He didn't try to rein this one in. 

“You know,” Cas said, and there was an air of wistfulness about him as he turned to look Dean in the eye, “I almost want to ask you about her. I know that’s a terrible idea, but...”

He trailed off then, his voice going small. He brought his eyes down, but leaned into the touch of Dean’s hand in his hair. The silence hung over them for a few prolong moments, and Dean felt that maybe Castiel was asking him to talk about Lisa anyway. 

_She’s wonderful. She’s beautiful and easy-going and a great mom and supportive and tough as all hell._

_But she’s not you,_ Dean wanted to say. _She’s not my true mate._  

Instead, he just kept moving his fingers softly through Castiel’s hair, his nail raking against his scalp like an affectionate pet. And, even though it was a bad idea, definitely, without debate, he leaned in and let his lips rest against the clammy skin of Castiel’s forehead. 

Cas released a pleased whimper, melting against Dean, until he seemed to remember himself and stood to his feet suddenly. “I don’t know about you,” he declared forcefully, “but I don’t care what time it is. I’m opening a bottle of wine.”

Dean swallowed loudly. “D’you have any whiskey?” he asked, half-joking. 

Castiel’s blue eyes pinned him to the spot. “That’s a much better idea.”

It only took two drinks before they were back on the sofa, knees touching and posture growing more relaxed. Another half a drink and they were at it again, hands tugging at collars and ripping at buttons, until Castiel was underneath him, fingers tugging at his hair and begging Dean to mark him with a bite. 

“Please, Alpha,” he moaned into Dean’s ear while his ass was slammed into at a steady pace, “show me I’m yours. Please, bite me, Dean, please.”

There was nothing that had ever turned Dean on the way it did when the omega underneath him moaned him name and begged him please. Jesus, he’d never even thought of himself as the dominant type. It wasn’t like he was any stranger to dirty talk, but with Lisa it was never like this. Fuck, it had never been like this. 

Dean nipped his teeth along Castiel’s neck and licked at the wounds as they started to turn purple before his eyes. That sight really got him going, looking at Cas’ neck and thinking how everyone would look at him and know; know that he had an alpha, that he belonged to someone, someone who knew how to take care of him, in every way. 

He was so close to letting go, to letting himself sink his teeth in like he wanted and just taking Castiel all for himself-- but he stopped himself. How the fuck he did it he had no idea, but just as he was about to pop his knot and go full-on fucking wild, he pulled his head up and shifted to Cas' mouth, to lock him in a heated embrace there instead of tearing into the muscles of his exposed neck like he wanted so badly to do. 

Because he knew that while Castiel really did belong to him, Dean himself still belonged to somebody else. He might be wrapped up in this omega in every way, shape and form, but he belonged to Lisa. For now. 

(-----)

From there, it just escalated exponentially. Now Dean was at Castiel’s apartment four nights a week, a fake gym habit invented to appease Lisa. He had to wear a t-shirt to sleep in every night, so that she wouldn’t see all the bruises Cas had left from their times together. 

Dean felt like it was so damn obvious on his face every time he looked at her. Like his eyes screamed, _I’m fucking someone else_. Sometimes she’d look at him and he’d think, that’s it, she knows, I’m done. 

He didn’t know why he didn’t just tell her, just come right out with it. Maybe, if it hadn’t been for Ben, he would have. But it was complicated. They were married. They’d taken vows. They had a mortgage and a joint bank account and game nights with shared friends and _a son_ together. He couldn’t just turn to her over dinner one night and say, _oh by the way I’ve found my true mate and it’s not you_. 

But, he did notice that things were changing, whether or not he intended them to. They stopped having sex almost completely, thought that wasn’t something totally new. Parenthood takes a toll on your bedroom activities, but now any energy Dean had left over (and then some) went to Cas. 

He tried to make up for it in little ways: made sure he was always touching her, always had a hand on her shoulder or her knee. If they were sitting on the couch, he’d take her feet and maneuver them into his lap. He also tried to flirt with her more often: he’d check her out when she crossed the room, grabbed her ass when they were out with friends. 

It was performance, all of it. Not that he’d lost all interest in Lisa. She was still as attractive as the day they’d met. But his heart wasn’t in it any longer. Every time he kissed her, it was like a betrayal to Cas, and that thought struck a chord much deeper inside him. 

Dean didn’t ever want to talk about Lisa to Castiel, but sometimes the omega would ask questions anyway. 

“Does she smell nice?” he asked one time. 

“What was she likes when she was pregnant?”

“Does she like it when you mutter Led Zeppelin lyrics in your sleep?”

Dean would try to deflect, just rub his hand over Cas’ cheek and stare into his ocean blue eyes, to keep things calm and easy. He was never quite sure why Castiel felt the need to ask. If he was trying to provoke some kind of guilt in Dean, or maybe in himself. 

“I know,” he said to Cas once when they were just cuddling on the sofa, having told Lis that he’d be out late with Benny and not to wait up, “that none of this is fair you. I know that… I should be stronger, braver. I should be able to be what you need. What you deserve.”

Castiel sat up in his arms like he might protest, but said nothing. Dean looked away, ashamed. “I wish things were different, Cas. I wish we’d met when we were sixteen or twenty-five, and we could have just gotten together right out of the gate, and right now we wouldn’t have to worry about anything in the world beside us.”

He drew his hands back in to himself. “If you want to go out and find someone else," he said in a grave tone, "I wouldn’t blame you. If you can’t wait, I understand.”

Castiel leaned up and pressed his lips delicately against Dean’s cheek. His eyes were misty, like they often were, even though he was smiling. “Even if I did want to be with anyone else, which I _don’t_ … I couldn’t do it. I don’t want to be with anyone else, ever. You’re my mate. I…”

His lips stopped moving but his eyes stayed focused on Dean’s. He couldn’t finish the thought, out of fear of what would happen once it was out in the open like that. 

Dean took Cas’ hand into his and swallowed. “I know. Me too.”

He might have smiled if he were anywhere else. He was in love with his True Mate, who loved him back. It was a happy occasion. Dean only wished that it felt like one. 

(-----)

And so it stayed that way, for months. Every Sunday night, Dean would go to bed next to his wife and think, this is the week. This week, I’ll tell her. 

And then life got in the way. He had a hard week at work, or else she did. It was Ben’s first week of tee-ball, or Lisa’s sister’s birthday party, or any one of the other thousand and one things that only proved to demonstrate how intertwined their lives had become. 

Also, the longer it went on, the more normal this whole thing became. Things that used to make him feel wracked with guilt barely even phased him now. Things that used to make Cas cry would barely even merit a shrug. And any feelings of paranoia had long since diminished into every day life. Lisa never even questioned him once. She trusted him, wholeheartedly. 

One night, when Dean had decided to spend the evening at home with Ben and Lisa, Ben ended up falling sick. He only picked at his pizza, which was the first sign something was wrong; and then, when they were sat on the couch in the living room watching _The Empire Strikes Back_ , he suddenly vomited, all over Lisa and the sofa. He immediately started crying, wailing loud, dramatic tears. Dean scooped him up and carried him into the bathroom, all the while he continued to yell and fuss as if it were the end of the world. 

"Calm down, buddy," Dean rubbed his hand over the fabric of Ben's shirt while he carried the boy, "You're all right. Dad's here."

Ben threw up one more time, just after Dean had finished cleaning him up, of course. They brushed his teeth and dressed him in his favorite PJs, and then Dean tucked him up into his big boy bed, with the _Cars_ sheets and his ratty old stuffed teddy right at hand. He sunk down onto his knees beside the bed and brushed Ben’s soft hair back from his forehead. 

“You feel okay, buddy?” he asked. Ben replied with a frown and a somber nod. Dean leaned in pressed his lips to the clammy skin of his forehead. “Good. That’s my brave little guy.”

A sigh came from behind him and the doorway, and he turned to see Lisa leaning against the doorframe. She was watching them with a muted smile. Dean shot her a wink and turned back to Ben. “How about Mom reads you a story, huh?”

Ben sniffled and muttered a weak, “Yes, please,” which was so adorable in its sadness that Dean had to hold back a pout. 

Dean gave him one more smile and then rose to his feet, just as Lisa started to approach the bed. As they crossed paths, he darted in quick to give her a kiss on the cheek. She flashed her teeth in that charming way she did and shooed him away flirtatiously. 

“I’m just gonna check on something, and I’ll be right back,” he said, even though Ben and Lisa were already ignoring him as she cracked open the front page of a  storybook. 

So he ducked out into the hallway and headed back toward the kitchen to grab his phone. He was waiting on an email from a prospective new client, true, but he also hadn’t heard from Cas since he’d left his place yesterday. He was hoping to have one of his funny little messages waiting for him. Cas always sent him the strangest, stream-of-consciousness texts, anything that popped into his mind. 

What he did find waiting for him, was something different altogether. 

There were three missed phone calls, and several messages. 

 _Dean,_ he’d written in the first message, _I think I’m going into heat. I’m leaving work now. I’m not sure if you can get away but I’d really like to have you tonight._

The second was a tad more risqué. _I’m touching myself thinking of you. Want you to be here, touching me, fingering me deep. Want to feel you inside me, Alpha, giving me what I need._

By the third text he was desperate. _Need you, please come. Your fingers, your cock. Need all of it. Please, Dean._

Before he’d even finished reading the last text message, a heat had emerged from deep within Dean’s inside, and he had already thrown the phone in his pocket and gone looking for his coat. 

He had to go to Cas. There just wasn’t any other option. Castiel was hurting and wanting and he needed Dean, needed his Alpha. 

Just the thought of Cas rolling around on his sheets, all slicked up and covered in sweat, his fingers working on himself like he couldn’t fucking get enough-- the thought had Dean rock hard in a way he’d never been in his entire life, including puberty. He wondered to himself if he was starting to rut-- he'd heard that happened sometimes with mates, true mate: one’s heat could set off the other’s rut, and vice versa. 

He didn’t have the time to think about that now. He had to get to Cas. 

He found his jacket thrown over the back of the sofa. His keys were inside the pocket. The second he heard their telltale jingling, he turned. 

“Don’t go.”

Dean’s brain was clouded, but he could hear those words. He turned around, slowly. Lisa was standing behind him, at the end of the hallway. Her arms were crossed over her chest, and she looked like she was asking, not telling. 

“Don’t go,” she said again, “Stay here with us.”

Dean choked on nothing. “Lis, I… I don’t--”

“I’m not as blind as you think,” she cut him off, taking a step forward and wrapping her arms more tightly around herself, “I know you don’t go to the gym. Four times a week, and you can barely open a jar of mayo? Come on, Dean.”

She laughed at the end, a little bit, like she didn’t want to come off as too harsh. 

“I don’t know who they are-- and I don’t want to know. Don’t… don’t tell me anything. Just stop it. Just stay here, with your wife and your son. Stay here and take care of us. Please, Dean. Stay.”

The words she spoke echoed in his hears. _Please, stay_. She had the same request as Castiel, and she sounded equally as desperate. He felt torn in two, ripped right down the middle. 

He wanted so much to be able to stay. For her, for Ben. He wished he was a better man. 

But every fiber of his goddamn body was screaming at him to get out that door and go to his omega. It was biology--and even more than that, it was what he wanted way down deep in the depths of his person. He couldn’t ignore that.

He opened his mouth to speak, at last, and the words came out as a sad, distant croak. “I… I can’t, Lisa. He’s my true mate.”

Lisa crumbled at the words. She folded forward and sucked in a gasp of air. She was crying now, and as Dean stood there in the fullest embodiment of remorse, he felt a tear trailing down his own face as well. 

His phone buzzed again in his pocket, and the alpha urges kicked back into gear. He turned back toward the door and took a step forward. “I’m so sorry,” he apologized in a small voice. “I’m so fucking sorry, Lis.”

The voice that rose up from behind him had ceased sounding small. Instead, it sounded full, and full of anger. “If you leave now, you will never see Ben again.”

Dean’s heart stopped cold inside his chest. He rotated, slowly, until he was face to face with the threatening glare Lisa was sending him. 

His face went soft, his eyes begging. “Don’t be like this. Please.”

Please, please, please. It’s all anyone could say around here. 

She continued to glare from the other end of the hall. They'd said everything they could. With nothing left to do, he took the final step out the door, and shut it behind him. 

He ran to his car and hopped in. Definitely drove too fast on his way across town and very nearly got into two different collisions, but he made it. He made it, and the minute he opened the door to Castiel’s apartment and the sweet scent of _heat mate mine_ hit him, it felt like everything was right in the world. 

“Dean?”

Cas’ voice was raw, rough, like he was parched and couldn’t find what he needed. Dean sprinted towards the bedroom, already ripping buttons off his shirt as he made his way. 

“I’m here, baby,” he shouted back, a promise and an apology at once. “I’m here, baby. I’m gonna take care of you.”

Castiel was on his bed, fully naked, a fake knot between his ass cheeks. His face flushed when Dean entered the room, as if embarassed to be found in what Dean knew instantly was the sexiest display he’d ever seen in his entire life. A hungry, predatory growl emanated from his throat, and Castiel’s eyes glazed over at the sound. 

“You didn’t answer, I… I didn’t think you’d…”

Dean leapt across the room to finally take his place next to Cas on the bed. All the alpha signals raging in his brain were quelled by his presence, his scent. “Shh, shh. Don’t worry," he soothed. "Can I get you anything? What do you need?”

Dean leaned down and inhaled deeply the delicious odor that sprang forth from Cas’ neck. It pleased him endlessly. It was perfection contained in one single thing. God, he loved Castiel so goddamn much. 

“Just need you,” the omega panted. “Need your knot. Been dreaming of it all day, Alpha.”

Another growl from Dean, and he leapt into action like a tiger called to battle. He took his time, worked Cas over with his hand and his tongue, split him wide open until he begged for release. He told him how good he was, what a perfect omega; told him he loved him. Dean felt like it was his truest purpose on this earth, doing this for Castiel at exactly that moment. He didn't have a single regret while he was buried inside his mate. 

After they’d finished, when Dean had made Castiel come twice, screaming both times, and they were tied together by the end of Dean’s inflated knot, Cas dotted kisses adorably over the surface of his lover’s face. “Thank you,” he whispered, sounding so much like the first day they’d met, “thank you for coming over and taking care of me. That was amazing. I’m sure it wasn’t easy to get away.”

Dean went stiff in his arms, which was difficult to do since he was so damn happy with his omega underneath him, lavishing his skin with all kinds of affection. “Uh, Cas?” he started, awkwardly.   

Cas looked up at him, his head tilted in that way that was so cute, it made Dean want to bury his nose in Cas’ neck and never come up for air. He wanted his pups to have that head tilt. He wanted his pups to be all Cas, just little miniatures of him running around who called Dean "daddy" and snuggled up in his arms.

Fuck. No thinking about that. He had to remind himself to go back to being distressed. It was so hard around Castiel.

“I told Lisa," he said at last. He could have said more. He tried to, but it didn't seem like there was anything else that needed to be said. 

Silence reigned over the room for a long time. 

“You told her about us?”

Dean nodded. 

Castiel withdrew his hands from Dean's face slowly, and spoke with trepidation when he asked, “What now?” 

It was a valid question. This was the moment they had been preparing for, hoping for, for months; the moment that they never really expected to come. Dean didn't have a picture of what the future looked like for them. So, the only answer he could give, what what he wanted to happen. 

“Now… I move in here, knock you up, and we start a life together. There’s nothing holding us back now.”

Cas’ eyes turned sad as his hands reached up to cup Dean’s face softly. “Are you sure? It’s so soon. It’s okay if you need time.”

Dean smiled, that confident smile he had that always made Castiel feel buoyed by it, “Castiel, baby. I’ve never been more sure of anything in my life.”

And even though it was true, that Dean finally felt he could start his life without any doubts about it being the right decision, there was still something tugging on the corner on his mind. He let himself be pulled by down Cas, into the most heated embrace; let himself be rolled over and ridden into absolute ecstasy, feeling the whole time like he’d finally connected the puzzle pieces that completed his perfect self, his perfect life. 

But all the while there was something that couldn’t quite let him enjoy the moment: two shadowy figures plaguing his vision, wrapped around his heart.

**Author's Note:**

> I also think is the smuttiest story I've ever written, so.... double unchartered territory.


End file.
